• Membrane Journal
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• v.14 no.2
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• pp.166-172
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• 2004

As a preliminary study for esterification membrane reactor used to produce 2,2,2-trifluoroethylmetacrylate (TFEMA), Pervaporation behaviors with crosslinked Poly(vinyl alcohol) composite membranes were investigated for aqueous TFEA (2,2,2-trifluoroethanol) feed solutions. In this study, crosslinked PVA composite membranes were prepared by reacting PVA with glutaraldehyde (CA)/acid catalyst onto porous polyethersulfone (PES) supports. SEH images (scanning electron microscopy) showed the thicknesses of selective coating layer was about 2-3 ${\mu}{\textrm}{m}$. The swelling tests showed the dogree of crosslinking decreased as content of the crosslinking agent, GA, increased. Total permeation flux decreased while separation factor increased as the CA content increased. As operating temperature increased, total permeation flux remarkably increased in the range of 85-95 wt% TFEA aqueous solutions. Interestingly, however, separation factor decreased in 85-90 wt% with operating temperature, while that increased in 95 wt%. In case of 90 wt% TFEA concentration and operating temperature 8$0^{\circ}C$, the PVA composite membrane crosslinked with 0.1 mol GA per PVA repeating unit showed high permeation flux of 1.5 kg/$m^2$hr and separation factor of 320. These results confirmed the applicability of the PVA composite membranes for the esterification membrane reactor of TFEMA.

• Journal of Chest Surgery
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• v.42 no.2
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• pp.157-164
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• 2009

Background: Various studies and experimental trials have been done to develop bioprosthetic devices to treat complex congenital heart disease due to the limited usage of homograft tissue. The purpose of the present study was to evaluate the effect of diamine bridges with using L-lysine, as compared with using ethanol. Material and Method: Porcine pericardium was fixed at 0.625% GA (commercial fixation). An interim step of ethanol (80%; 1 day at room temperature) or L-lysine (0.1 M; 2 days at $37^{\circ}C$) was followed by completion of the GA fixation (2 days at $4^{\circ}C$ and 7 days at room temperature). The tensile strength and thickness of the porcine percardium were measured, respectively. The treated pericardiums were implanted subcutaneously into three-week old Long-Evans rats for 8 weeks. The calcium content of the implants was assessed by atomic absorption spectroscopy and the histology. Result: Ethanol pretreatment ($13.6{\pm}10.0ug/mg$, p=0.008), L-lysine pretreatment ($15.3{\pm}1.0 ug/mg$, p=0.002), and both treatment ($16.1{\pm}11.1ug/mg$, p=0.012) significantly inhibited calcification, as compared with the controls $(51.2{\pm}8.5ug/mg)$. L-lysine pretreatment ($0.18{\pm}0.02mm,\;1.20{\pm}0.30kg$ f/5 mm) significantly increased the thickness and tensile strength, as compared with ethanol pretreatment ($0.13{\pm}0.03mm,\;0.85{\pm}0.36$ 1.0 kg f/5 mm) (p<0.01, p=0.035). Conclusion: The diamine bridges using L-lysine seemed to decrease the calcification of porcine pericardium fixed with glutaraldehyde, and this was comparable with Ethanol. Additionally, it seemed to enhance the thickness and tensile strength.

• Textile Coloration and Finishing
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• v.30 no.4
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• pp.264-274
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• 2018

Immobilization of lysozyme on chitosan non-woven using glutaraldehyde(GA) was investigated. For this, 100 % chitosan non-woven was prepared as novel support for the enzyme immobilization. In addition, free lysozyme activity was examined depending on various pH and temperature by measuring time. Moreover, the optimum immobilization conditions depending on various pH, temperature, immobilization time and lysozyme concentration was evaluated. In addition, thermal stability and storage stability of immobilized lysozyme were measured. The characteristics of immobilized lysozyme was examined by FT-IR, surface morphology, and MTT assay. The results are follows: the optimal immobilization of lysozyme were pH 7.0, $25^{\circ}C$, lysozyme concentration 1.5 mg/ml, immobilization time 240 min. The immobilized lysozyme showed higher thermal stability than the free trypsin. The immobilized lysozyme activity was retained 80 % of its initial activity at $4^{\circ}C$ over 30 days of storage. The lysozyme was immobilized effectively on chitosan non-woven by observation of surface morphology.

• Journal of Microbiology and Biotechnology
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• v.22 no.11
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• pp.1486-1493
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• 2012

In this study, we investigated whether galactooligosaccharide (GOS) can be stably and steadily synthesized using immobilized ${\beta}$-galactosidase (${\beta}$-gal) inclusion body (IB)-containing E. coli cells during long-term repeated-batch operation. To improve the operational stability of this enzyme reactor system, immobilized E. coli cells were crosslinked with glutaraldehyde (GA) after immobilization of the E. coli. When we treated with 2% GA for E. coli crosslinking, GOS production continued to an elapsed time of 576 h, in which seven batch runs were operated consecutively. GOS production ranged from 51.6 to 78.5 g/l ($71.2{\pm}10.5$ g/l, n = 7) during those batch operations. In contrast, when we crosslinked E. coli with 4% GA, GOS production ranged from 31.5 to 64.0 g/l ($52.3{\pm}10.8$, n = 4), and only four consecutive batch runs were operated. Although we did not use an industrial ${\beta}$-gal for GOS production, in which a thermophile is used routinely, this represents the longest operation time for GOS production using E. coli ${\beta}$-gal. Improved stability and durability of the cell immobilization system were achieved using the crosslinking protocol. This strategy could be directly applied to other microbial enzyme reactor systems using cell immobilization to extend the operation time and/or improve the reactor system stability.

• Journal of Chest Surgery
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• v.44 no.2
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• pp.99-107
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• 2011

Background: Calcification is the most frequent cause of clinical failure of bioprosthetic tissues fabricated from GA-fixed porcine valves or bovine pericardium. A multi-factorial approach using different mechanisms was recently developed to reduce the calcification of bioprosthetic tissues. The purpose of the present study was to evaluate the synchronized synergism of using L-arginine and $NaBH_4$, compared with ethanol and L-lysine, in glutaraldehyde treated porcine pericardium from the standpoint of calcification and tissue elasticity. Materials and Methods: Porcine pericardium was fixed at 0.625% GA (7 days at room temperature after 2 days at $4^{\circ}C$). An interim step of ethanol (80%; 1 day at room temperature) or L-lysine (0.1 M; 2 days at $37^{\circ}C$) or L-arginine (0.1 M; 2 days at $37^{\circ}C$) was followed by completion of the GA fixation. A final step of NaBH4 (0.1 M; 2 days at room temperature) was followed. Their tensile strength, thickness, and thermal stability were measured. Treated pericardia were implanted subcutaneously into three-week-old Sprague-Dawley rats for 8 weeks. Calcium content was assessed by atomic absorption spectroscopy and histology. Results: L-arginine and $NaBH_4$ pretreatment ($1.81{\pm}0.39$ kgf/5 mm p=0.001, $0.30{\pm}0.08$ mm p<0.001) significantly increased tensile strength and thickness compared with the control ($0.53{\pm}0.34$ kgf/5 mm, $0.10{\pm}0.02$ mm). In a thermal stability test, L-arginine and $NaBH_4$ pretreatment ($84.25{\pm}1.12^{\circ}C$, p=0.023) caused a significant difference from the control ($86.25{\pm}0.00^{\circ}C$). L-lysine and $NaBH_4$ pretreatment ($183.8{\pm}42.6$ ug/mg, p=0.804), and L-arginine and $NaBH_4$ pretreatment ($163.3{\pm}27.5$ ug/mg, p=0.621) did not significantly inhibit calcification compared to the control ($175.5{\pm}45.3$ ug/mg), but ethanol and $NaBH_4$ pretreatment did ($38.5{\pm}37.3$ ug/mg, p=0.003). Conclusion: The combined pretreatment using L-arginine and $NaBH_4$ after GA fixation seemed to increase the tensile strength and thickness of porcine pericardium, fixed with GA. Additionally, it seemed to keep thermal stability. However it could not decrease the calcification of porcine pericardium fixed with GA. $NaBH_4$ pretreatment seemed to decrease the calcification of porcine pericardium fixed with GA, but only with ethanol.

• Polymer(Korea)
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• v.38 no.6
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• pp.687-693
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• 2014

Poly(ether-block-amide) 1657 (PEBAX 1657) blended membranes with molecular weight 400 poly(ethylene glycol) (PEG 400) were prepared and their permeability was tested for the gases $N_2$, $O_2$, $CH_4$, $CO_2$, and $SO_2$ by the time-lag method. The permeation characteristics were investigated in terms of diffusivity and solubility, which are dominant factors for gas transport. With the addition of PEG 400, the permeability of all the gases increased and also the ideal selectivity for several pair gases was enhanced. In particular, selectivity for $CO_2/N_2$ ranged from 53.2 (pristine PEBAX 1657 membrane) to 84.1 (50% PEG 400 added), for $SO_2/CO_2$ from 38.9 to 50.7, and for $CO_2/CH_4$ from 17.7 to 31.4. The increase of both permeability and selectivity is mainly because of the increase of solubility of the gases, especially $CO_2$ and $SO_2$. To obtain durability against water vapor, glutaraldehyde (GA) was added to the PEBAX 1657/PEG 400 blended membranes. As a result, permeability decreased owing to a reduction of the free volume and ether oxide units, which are the main factors in elevating the permeability for the blended membranes, and selectivity decrease however; we believe that the durability of the resulting membranes would be increased.

• Journal of Chest Surgery
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• v.32 no.11
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• pp.998-1003
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• 1999

Background: Bovine pericardium treated with glutaraldehyde(GA) is one of the most popular prosthetic materials. However, its late calcific degeneration after implantation results in early failure of the prosthesis. Therefore, we investigated the effects of combined treatment with sodium dodecyl sulfate(SDS) and glutamate on calcific degeneration of GA treated bovine pericardium. Material and Method: Sixty square-shaped pieces of bovine pericardia were fixed in 0.625% GA solution with 4g/L MgCl2.6H2O as a control group (group 1). Sixty pieces pretreated with 1% SDS (group 2) and sixty pieces posttreated with 8% glutamate (group 3) were also fixed in the same GA solution. Sixty pieces pretreated with 1% SDS and posttrated with 8% glutamate were also fixed in the same GA solution (group 4). After 1 month of fixation, the pieces were implanted into the belly of sixty Sprague-Dawley rat subdermally and were extracted 1 month, 2 months and 3 months after the implantation. With an atomic absorption spectrophotometry, we measured the calcium amount deposited. Result: The calcium deposition in 1 month was 2.01$\pm$0.13 mg/g in group 1, 1.45$\pm$0.31 mg/g in group 2, 2.49$\pm$0.15 mg/g in group 3 and 0.75$\pm$0.27 mg/g in group 4. In 2 months, it was 3.57$\pm$0.15 mg/g in group 1, 0.98$\pm$0.30 mg/g in group 2, 3.46$\pm$0.12 mg/g in group 3, and 1.48$\pm$0.39 mg/g in group 4, and 5.45$\pm$0.42 mg/g in group 1, 2.43$\pm$0.53 mg/g in group 2, 4.20$\pm$0.55 mg/g in group 3, and 1.02$\pm$0.27 mg/g in group 4 in 3 months. The calcium depositions in group 2 and 4 were less than those of group 1 and 3 in 1 month 2, months, and 3 months(p<0.01). The calcium depositions in group 1, 2 and 3 increased with time. However, they remained unchanged in group 4, which was statistically significant(p<0.01). Conclusion: Pretreatment with SDS is effective in reducing calcification of GA treated bovine pericardium, and the combined method of pretreatment with SDS and posttreatment with glutamate was more effective than the other methods.

• Journal of Chest Surgery
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• v.29 no.1
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• pp.7-13
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• 1996

The conventional glutaraldehyde (GA) fixation method of tissue valves is considered to be responsible for accelerated valve degeneration. The release of toxic GA from the valve tissue is believed to limit endothelial cell (EC) ingrowth. Removal of toxic GA by reaction with L-glutamic acid and storage in a Paraben solution may offer good EC growth. To investigate the conditions for endothelialization of tissue valves, the growth properties of ECs on the conventionally and alternatively treated pericardial tissue were compared. Conventional preparation included zero-pressure fixation for 72 hours in phosphated-buffered saline (PBS) solution containing 0.5% GA at 4$^{\circ}C$ and storage into PBS containing 0.2% GA(group I). Alternatively treated pericardial tissues were divided into three postfixation treatment groups : (1) storage in PBS solution containing Paraben(group II), (2) treatment with PBS containing 8$^{\circ}C$ L-glutamic acid(PH 7.35) and storage in PBS solution containing Paraben (g oup III), (3) treatment with L-glutamic acid dissolved in distilled water (PH 3.5) (group IV). Pericardial tissue were transferred into the 24-well plate after storage for 4 weeks. ECs were harvested enzymatically from the bovine pulmonary artery and grown to confluence on culture flask surfaces. Detached ECs by trypsin were incubated into the each well of the 24-well plate including test pericardial tissues. Cells were detached by trypsin, 1, 2, 3, 5, 7 days after incubation and counted on the hemacytometer. Cell viability test was performed by frypan-blue exclusion method. Acute cell death in the group I were found even after prolonged washing. The group II showed prolonged cell survival compared with the group I. Both group III and group IV showed better cell growth than group II. There was no statistically significant difference between group III and group IV method in terms of EC growth. This results suggest that treatment by L-glutamic ac id and storage in a Paraben solution be a promising approach for improvement of durability of GA-treated tissue valves.

• Journal of Chest Surgery
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• v.36 no.3
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• pp.131-135
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• 2003

Bovine pericardium fixed in glutaraldehyde solution (GA) has been one of the most popular surgical bioprosthesis, however, late calcific degeneration after implantation remains to be solved. To mitigate calcific degeneration, we posttreated the bovine pericardium with amino acids after GA fixation. Material and Method: 40 small pieces of bovine pericardia were fixed in 0.625% GA solution with 4 g/L $MgCl_26H_2O$as a control group (group 1). 40 pieces fixed in the same GA solution were posttreated with 2% chitosan solution (group 2) and the other 40 pieces posttreated with 8% glutamate (group 3). These were implanted into the belly of forty Fisher 344 rats subdermally and extracted at f month, 2 months, 3 months and 4 months after implantation. Result: With atomic absorption spectrophotometry we measured the deposited calcium amount and the results were as follows; 2.01 $\pm$0.13 mg/g in group 1, 2.34$\pm$0.73 mg/g in group 2, 2.49$\pm$0.15 mg/g in group 3 at 1 month after implantation, and 3.57$\pm$0.15 mg/g in group 1, 3.52$\pm$0.92 mg/g in group 2, 3.46$\pm$0.12 mg/g in group 3 at the second month. But 5.45$\pm$0.42 mg/g in group 1, 3.22 $\pm$1.31 mg/g in group 2 and 4.20$\pm$0.55 mg/g in group 3 at the 3rd month, which have statistical significance in group 2 (p<0.05). Finally at 4th month, 6.01$\pm$1.21 mg/g in group 1, 3.78$\pm$1.82 mg/g in group 2, 3.92$\pm$0.92 mg/g in group 3, which also have statistical significance (p < 0.05). Conclusion: This means posttreatment with 2% chitosan shows meaningful calcium mitigation effects after 3rd month on subcutaneously implanted bovine pericardium in the rat models but 8% glutamate shows mitigation effect after 4months in this experiment.

• Macromolecular Research
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• v.11 no.4
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• pp.291-295
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• 2003

Dextran as a candidate material for colon-specific drug delivery has been studied. Crosslinked dextran hydrogels were prepared by mixing dextran, $MgCl_2$, glutaraldehyde (GA) and polyethyleneglycol (PEG 400) in water. The dextran hydrogels were characterized by measuring equilibrium swelling ratios and mechanical strengths. Response surface methodology (Central Composite Design) was used to evaluate the swelling behaviors and mechanical strengths as functions of concentrations of $MgCl_2$, GA, and PEG 400, which was found to be useful for the evaluation. It showed that the swelling behavior and mechanical strengths were influenced significantly by PEG 400 and $MgCl_2$ concentrations.